View Code of Problem 71

#include <stdio.h>
//有一分数序列： 2/1 3/2 5/3 8/5 13/8 21/13...... 求出这个数列的前N项之和，保留两位小数。 
int main()
{
  int n,i;
  double c,temp,sum = 0,a = 1.0,b = 1.0;
  scanf("%d",&n);
  for(i=0;i<n;i++)
  {
    temp = a;
	a = b;
	b = temp + b;
    c = b/a;
    sum+=c;
  }
  printf("%.2lf",sum);
  return 0;
}